0:00

So moving on to part two, we're going

0:02

to have a look at some normal structures which have uptake

0:05

on Gallium 68 P SM A.

0:07

And we did visit this very early on,

0:09

but it's worthwhile going through it one more time

0:12

because understanding the physiological uptake

0:14

of the tracer is so important to determining

0:16

what is normal and what is abnormal.

0:18

So with our rotating MIP, you can see that there's a lot

0:21

of black going on and this is a normal study.

0:23

So we see uptake in the sali and lacrimal glands.

0:26

We see some uptake in the liver

0:28

and spleen, the bowel, the kidneys, and the bladder

0:33

and ureters because the tracer is urinary,

0:35

has urinary excretion.

0:37

And as we saw early on, we will go back

0:40

through the physiological uptake again.

0:42

So we're on pet rainbow, no uptake in the brain usually.

0:46

Um, we see our lacrimal glands coming down, intens avidity

0:51

through our avidity, which is a good word

0:53

for intensity uptake through our saliva glands a little bit,

0:56

um, through the um, nasopharynx

0:58

and oropharynx which is can be normal.

1:00

You can see a little bit up in inflammation.

1:02

Um, that's all normal coming through.

1:04

A little bit of uptake in the thyroid is normal.

1:06

And then we are seeing our ganglia, which we'll come back

1:09

and look at the anatomy of in a moment, um, coming down

1:12

through the mediastinum

1:13

and we've got a bit of uptake still through the blood.

1:16

Um, blood pool we call.

1:17

Um, but that's just normal physiological background.

1:20

And then coming down a little bit in the esophagus

1:23

but not too much green isn't too high on the pet scale.

1:25

Hot spleen, hot liver, hot kidney.

1:29

Then all the way down we're seeing our kidneys

1:31

with the ureters as we saw.

1:34

Hot ureter, hot ureter, bowel, that's all nice and normal.

1:38

Then coming down into the bladder here

1:42

and that's all part of our normal study.

1:45

And here with a patient who does have prostate cancer,

1:49

this is intense focal uptake in the region of the prostate.

1:52

And this is the background avidity

1:54

and prost toor prostate tissue does have some

1:56

PSMA receptor expression.

1:58

Um, but it's typically not this hot.

2:00

So we are remembering from the earlier sessions

2:02

that PSMA expression is upregulated in

2:05

some prostate cancer cells.

2:06

Um, but a little bit of heterogeneous uptake in

2:08

the prostate is normal.

2:11

Um, and here it is our rotating mip.

2:13

And so MIP is maximum intensity projection

2:17

and we will see that there is something kind

2:19

of hanging out here on this particular mip.

2:21

So we might have to go back.

2:24

So if I stop, let him turn around.

2:27

You can see that there's a little.here

2:28

coming around the spleen.

2:30

So is that a node?

2:32

Probably not, not usual for a patient to have a node, um,

2:36

lying out there so far away laterally in the abdomen.

2:39

So we know we can cross that one off.

2:41

Could it be a peritoneal deposit?

2:42

Maybe we can go back

2:45

and have a look at the avidity of the spleen,

2:48

which is quite warm

2:49

and it's similar in avidity to the spleen.

2:51

So we will go back to our study here

2:55

and see how hot that spleen is.

2:57

And then coming down just

2:58

Next to it is this little uptake

3:01

and I'll just pause it so we can scroll back up again.

3:06

And I will tell you that when we turned off the fusion,

3:09

that was a S spinal oculus.

3:11

So anatomical um, variation is something

3:13

to be really be aware of, particularly in those structures

3:16

that we know will have PSMA uptake like the spleen,

3:19

like the kidneys, um, liver and bowel.

3:22

So that was a sulu.

3:25

Um, in this patient here, there's a few things to kind

3:28

of also take note of.

3:29

And here we've got our injection site, our cannula,

3:31

no he doesn't have a met in his arm.

3:32

This is where we injected the tracer.

3:34

And a little bit has been residual just where

3:36

that cannulate injection site was.

3:38

But also on here there's some dots you can see

3:40

through the zillion through the mediastinum.

3:42

And these are gonna be just normal or reactive lymph nodes.

3:45

Um, they're non enlarged by size criteria.

3:46

They don't have that intense uptake like we're seeing here.

3:49

Like it's a good kind of, you know,

3:51

surrogate internal measure to think about

3:52

how hot the S library glands are.

3:54

They're not really popping up.

3:56

So that kind of degree

3:57

of uptake a lymph node I would downplay.

3:59

And here are those two dots that we saw

4:01

before related to the ganglia.

4:04

And the ganglia are a really interesting structure

4:07

that you really don't see on many other imaging modalities,

4:10

but you do see it on PSMA pet.

4:13

And here we can see one in the upper abdomen as well.

4:16

And to kind of just do a little bit more

4:17

of a deep dive on this and if you can kind of understand

4:19

where the ganglia are and the variability of uptake,

4:23

it can prevent you from over calling these as lymph nodes,

4:25

which can be a bit of a pitfall.

4:28

So I've borrowed a couple of cases

4:30

and slides from colleagues of mine, Dr.

4:32

Ashvin Raghavan and Dr. Ed.

4:34

She and they did a beautiful poster on this.

4:37

And so we can see here these are some examples of ganglia

4:40

and on the top row we've got the stellate ganglia indicated

4:43

by the yellow arrows and then on the bottom level

4:45

as well just in that coronal reconstruction.

4:47

And you can really see that there is quite pronounced uptake

4:50

in these tiny little beam structures which

4:52

are the stellate ganglia.

4:54

And these are formed

4:55

by bringing together the inferior cervical ganglion in the

4:58

upper thoracic ganglion.

5:00

Um, and it gives this kinda stellate shape just at the

5:02

thoracic inlet there.

5:04

And we tend to see similar uptake in the region

5:08

of the celiac, um, ganglion as well in the upper abdomen.

5:12

And here's a good example here of the celiac ganglion.

5:16

Um, again indicated by the yellow arrows showing kind

5:19

of asymmetric uptake in this kind of, you know,

5:21

elongated structure here in a typical anatomical location,

5:25

often bilateral but sometimes

5:27

asymmetrical in terms of its uptake.

5:29

What's been really interesting about total body PET

5:32

and also digital pet scanners is we are now getting much,

5:35

much better in terms of our resolution,

5:37

our spatial resolution for imaging these patients.

5:40

And so we're starting to see smaller and smaller structures.

5:42

And so I have noticed in years that we are now starting

5:44

to see sacral ganglia.

5:46

And so here's our celiac ganglia here,

5:48

but we also have the upper sacral ganglion.

5:52

And this is now becoming more and more clinically relevant

5:54

because the presacral region is an area that we have

5:57

to really closely scrutinize for abnormal uptake

6:00

to indicate nodal disease.

6:02

So here's a great slide that they had. Are these, no.

6:06

And so the position of these ones, they're quite warm

6:09

as you can see, quite avid indicated by the yellow arrows,

6:12

is to look at the relationship between the sacral foramina

6:16

and I think this is just a great slide.

6:17

It's reconstructed in a way

6:18

that you can see the ganglia just anterior to this.

6:21

Um, and so their bilateral often both have will have uptake.

6:24

There may be some asymmetry,

6:26

but that anatomical location can be really useful.

6:29

That said, sometimes you can't be definitive

6:31

and if that's the case, you know,

6:32

you just describe what you see.

6:34

Here's another really great case just to kind

6:36

of round us out talking about ganglia

6:38

with our improved resolution on our PET scans.

6:40

As you can see that every single foramen has a little

6:43

ganglia here, seen

6:45

as purple indicated with the yellow arrows.

6:47

So we're not just seeing the major ganglia anymore.

6:49

Um, we're seeing little smaller structures within those

6:52

neural exit frame it.

6:53

So if it is in a typical location for a neural structure,

6:55

you're seeing just a little bit of uptake,

6:57

um, it's quite focal.

6:58

And think about whether or not you may be looking at

7:00

ganglia.